Crank for a bicycle



FIG. 1 is a front-right and side-top perspective view of a crank for a bicycle, showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof (the right side elevational view being a mirror image thereof);

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a crank for a bicycle, as shown and described. 